[Gagecoalbrace]

there are a set of games that this anime is based off of. 巨乳ファンタジー by waffle or Busty fantasy for a rough translation. there are 4 games so far

the first, a gaiden, a spin-off, and a sequel

巨乳ファンタジー 2 is the most recent and the only returning is the succubus.

the first episode has subs so you can hear a basic story of the first part of the first game. I found it at hshare.net but that is just me. also found all but the first and the second game there (used to have the first but old site kinda kicked the bucket and had to try and recover what he could).